diff --git a/src/core/vite-plugins/devHtmlPrerender.ts b/src/core/vite-plugins/devHtmlPrerender.ts
index 49a0a7c9..95e2f960 100644
--- a/src/core/vite-plugins/devHtmlPrerender.ts
+++ b/src/core/vite-plugins/devHtmlPrerender.ts
@@ -11,20 +11,17 @@ export function devHtmlPrerender(config: InternalConfig): vite.Plugin {
   return {
     apply: 'build',
     name: 'wxt:dev-html-prerender',
-    config(userConfig) {
-      return vite.mergeConfig(
-        {
-          resolve: {
-            alias: {
-              '@wxt/reload-html': resolve(
-                config.root,
-                'node_modules/wxt/dist/virtual-modules/reload-html.js',
-              ),
-            },
+    config() {
+      return {
+        resolve: {
+          alias: {
+            '@wxt/reload-html': resolve(
+              config.root,
+              'node_modules/wxt/dist/virtual-modules/reload-html.js',
+            ),
           },
         },
-        userConfig,
-      );
+      };
     },
     async transform(html, id) {
       const server = config.server;
diff --git a/src/core/vite-plugins/devServerGlobals.ts b/src/core/vite-plugins/devServerGlobals.ts
index 525b3600..5ab99349 100644
--- a/src/core/vite-plugins/devServerGlobals.ts
+++ b/src/core/vite-plugins/devServerGlobals.ts
@@ -7,18 +7,19 @@ import { InternalConfig } from '../types';
 export function devServerGlobals(internalConfig: InternalConfig): Plugin {
   return {
     name: 'wxt:dev-server-globals',
-    config(config) {
+    config() {
       if (internalConfig.server == null || internalConfig.command == 'build')
         return;
 
-      config.define ??= {};
-      config.define.__DEV_SERVER_PROTOCOL__ = JSON.stringify('ws:');
-      config.define.__DEV_SERVER_HOSTNAME__ = JSON.stringify(
-        internalConfig.server.hostname,
-      );
-      config.define.__DEV_SERVER_PORT__ = JSON.stringify(
-        internalConfig.server.port,
-      );
+      return {
+        define: {
+          __DEV_SERVER_PROTOCOL__: JSON.stringify('ws:'),
+          __DEV_SERVER_HOSTNAME__: JSON.stringify(
+            internalConfig.server.hostname,
+          ),
+          __DEV_SERVER_PORT__: JSON.stringify(internalConfig.server.port),
+        },
+      };
     },
   };
 }